When a sensor ages during the life cycle of the device with which it is associated, its accuracy can be lowered and the return value can include an offset when compared with a nominal characteristic curve. In the specific case of a position sensor which is typically used in a variable geometry turbocharger (VGT) for an internal combustion engine (particularly a diesel engine) for a motor-vehicle, the nominal characteristic curve is a straight line. Alteration of the characteristic curve caused by ageing of the sensor or due to manufacturing tolerances may result in an invariable offset throughout the whole operating range (i.e., the range of measured values), thus simply causing a translation of the characteristic curve to an actual curve parallel to the nominal one, or in a variable offset throughout the operating range, thus determining an actual characteristic curve having a different slope from the nominal one.
In a control system for the fluid control device, whose strategy is based on a closed loop control along with a feed-forward control, both operating according to the values returned by the sensor, a characteristic curve for the sensor which is different from the nominal one due to an offset of the sensor causes a lowered response time in the system.
It is at least one object of the present invention to minimize the impact of an offset of a position sensor due to ageing or manufacturing tolerances on a control system for a fluid control device in an internal combustion engine, so that the performance of the control is not lowered. In addition, other objects, desirable features, and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.